Fig. 5

Expression of P-element piRNAs derived from P elements in F1 hybrids. a Small RNA sequencing reads (24–35 nt long) in testes (upper) and F1 ovaries (lower) were mapped to the sense (green) and antisense (red) strands of the P-element. The P-element structure is schematically shown at the bottom. b The positive relationship between occupancy-adjusted relative copy number of piRNA cluster-embedded P elements (the fraction of DNA reads supporting P-element insertion in clusters, x-axis) and the expression level of P-element piRNAs in F1 (CS female x test male) ovaries (y-axis). The Pearson’s R and p values are indicated on the top. c, d The expression levels of P-element piRNAs in the ovaries of young (2- to 3 days old) F1 hybrids (c) and in 0–24 h whole embryos of F1 hybrid (d). P-element piRNA reads were normalized by miRNA reads (RPM, reads per million miRNA reads)